As the incremental API is now used in several transforms, printing
the whole dominator tree creates a lot of noise when running with
the `-debug` flag. This patch fixes that.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@311176 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This patch teaches ADCE to preserve both DominatorTrees and PostDominatorTrees.
I didn't notice any performance impact when bootstrapping clang with this patch.
The patch was originally committed in r311039 and reverted in r311049.
This revision fixes the problem with not adding a dependency on the
DominatorTreeWrapperPass for the LegacyPassManager.
Reviewers: dberlin, chandlerc, sanjoy, davide, grosser, brzycki
Reviewed By: davide
Subscribers: grandinj, zhendongsu, llvm-commits, david2050
Differential Revision: https://reviews.llvm.org/D35869
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@311057 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This patch teaches ADCE to preserve both DominatorTrees and PostDominatorTrees.
I didn't notice any performance impact when bootstrapping clang with this patch.
Reviewers: dberlin, chandlerc, sanjoy, davide, grosser, brzycki
Reviewed By: davide
Subscribers: grandinj, zhendongsu, llvm-commits, david2050
Differential Revision: https://reviews.llvm.org/D35869
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@311039 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This patch introduces a way of informing the (Post)DominatorTree about multiple CFG updates that happened since the last tree update. This makes performing tree updates much easier, as it internally takes care of applying the updates in lockstep with the (virtual) updates to the CFG, which is done by reverse-applying future CFG updates.
The batch updater is able to remove redundant updates that cancel each other out. In the future, it should be also possible to reorder updates to reduce the amount of work needed to perform the updates.
Reviewers: dberlin, sanjoy, grosser, davide, brzycki
Reviewed By: brzycki
Subscribers: mgorny, llvm-commits
Differential Revision: https://reviews.llvm.org/D36167
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@311015 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This patch teaches PostDominatorTree about infinite loops. It is built on top of D29705 by @dberlin which includes a very detailed motivation for this change.
What's new is that the patch also teaches the incremental updater how to deal with reverse-unreachable regions and how to properly maintain and verify tree roots. Before that, the incremental algorithm sometimes ended up preserving reverse-unreachable regions after updates that wouldn't appear in the tree if it was constructed from scratch on the same CFG.
This patch makes the following assumptions:
- A sequence of updates should produce the same tree as a recalculating it.
- Any sequence of the same updates should lead to the same tree.
- Siblings and roots are unordered.
The last two properties are essential to efficiently perform batch updates in the future.
When it comes to the first one, we can decide later that the consistency between freshly built tree and an updated one doesn't matter match, as there are many correct ways to pick roots in infinite loops, and to relax this assumption. That should enable us to recalculate postdominators less frequently.
This patch is pretty conservative when it comes to incremental updates on reverse-unreachable regions and ends up recalculating the whole tree in many cases. It should be possible to improve the performance in many cases, if we decide that it's important enough.
That being said, my experiments showed that reverse-unreachable are very rare in the IR emitted by clang when bootstrapping clang. Here are the statistics I collected by analyzing IR between passes and after each removePredecessor call:
```
# functions: 52283
# samples: 337609
# reverse unreachable BBs: 216022
# BBs: 247840796
Percent reverse-unreachable: 0.08716159869015269 %
Max(PercRevUnreachable) in a function: 87.58620689655172 %
# > 25 % samples: 471 ( 0.1395104988314885 % samples )
... in 145 ( 0.27733680163724345 % functions )
```
Most of the reverse-unreachable regions come from invalid IR where it wouldn't be possible to construct a PostDomTree anyway.
I would like to commit this patch in the next week in order to be able to complete the work that depends on it before the end of my internship, so please don't wait long to voice your concerns :).
Reviewers: dberlin, sanjoy, grosser, brzycki, davide, chandlerc, hfinkel
Reviewed By: dberlin
Subscribers: nhaehnle, javed.absar, kparzysz, uabelho, jlebar, hiraditya, llvm-commits, dberlin, david2050
Differential Revision: https://reviews.llvm.org/D35851
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310940 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This patch moves root-finding logic from DominatorTreeBase to GenericDomTreeConstruction.h.
It makes the behavior simpler and more consistent by always adding a virtual root to PostDominatorTrees.
Reviewers: dberlin, davide, grosser, sanjoy
Reviewed By: dberlin
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D35597
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@309146 91177308-0d34-0410-b5e6-96231b3b80d8
Summary: This patch improves error detection in deleteEdge. It asserts that the edge doesn't exist in the CFG and that DomTree knew about this edge before.
Reviewers: dberlin, grosser, brzycki, sanjoy
Reviewed By: dberlin
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D35571
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@308354 91177308-0d34-0410-b5e6-96231b3b80d8
This fixes a minor bug in insertion to a reachable node that caused
DominatorTree.InsertDeleteExhaustive flakiness. The patch also adds
a new testcase for this exact failure.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@308074 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This patch implements incremental edge deletions.
It also makes DominatorTreeBase store a pointer to the parent function. The parent function is needed to perform full rebuilts during some deletions, but it is also used to verify that inserted and deleted edges come from the same function.
Reviewers: dberlin, davide, grosser, sanjoy, brzycki
Reviewed By: dberlin
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D35342
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@308062 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This patch introduces incremental edge insertions based on the Depth Based Search algorithm.
Insertions should work for both dominators and postdominators.
Reviewers: dberlin, grosser, davide, sanjoy, brzycki
Reviewed By: dberlin
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D35341
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@308054 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This patch adds `BlockPrinter`-- a small wrapper for printing CFG nodes and DomTree nodes to `raw_ostream`. It is meant to be only used internally, for debugging and printing errors.
Reviewers: dberlin, sanjoy, grosser, davide
Reviewed By: grosser, davide
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D35286
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@308036 91177308-0d34-0410-b5e6-96231b3b80d8
Summary: DominatorTreeBase and related classes used overcomplicated template machinery. This patch simplifies them and gets rid of DominatorTreeBaseTraits and DominatorTreeBaseByTraits, which weren't actually used outside the DomTree construction.
Reviewers: dberlin, sanjoy, davide, grosser
Reviewed By: dberlin, davide, grosser
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D35285
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@307953 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This patch splits the SemiNCA algorithm into smaller functions. It also adds a new debug macro.
In order to perform incremental updates, we need to be able to refire SemiNCA on a subset of CFG nodes (determined by a DFS walk results). We also need to skip nodes that are not deep enough in a DomTree.
Reviewers: dberlin, davide, sanjoy, grosser
Reviewed By: dberlin, davide
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D35282
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@307950 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This patch improves verification by making `verifyReachablility` look for CFG not found in the DomTree.
It also makes the verification work with postdominators by handling virtual root.
Reviewers: dberlin, davide, grosser, sanjoy
Reviewed By: dberlin
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D35279
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@307936 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Custom DFS implementation allows us to skip over certain nodes without adding them to the visited map, which is not easily doable with llvm's dfs iterators. What's more, caching predecessors becomes easy.
This patch implements a single DFS function (template) for both forward and reverse DFS, which should be easier to maintain then separate two ones.
Skipping over nodes based on a predicate will be necessary later to implement incremental updates.
There also seems to be a very slight performance improved when bootstrapping clang with this patch on my machine (3:28s -> 3:26s) .
Reviewers: dberlin, sanjoy, davide, grosser
Reviewed By: dberlin
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D34651
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@307727 91177308-0d34-0410-b5e6-96231b3b80d8
This reverts commit r306907 and reapplies the patches in the title.
The patches used to make one of the
CodeGen/ARM/2011-02-07-AntidepClobber.ll test to fail because of a
missing null check.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@306919 91177308-0d34-0410-b5e6-96231b3b80d8
This reverts commit r306894.
Revert "[Dominators] Add NearestCommonDominator verification"
This reverts commit r306893.
Revert "[Dominators] Keep tree level in DomTreeNode and use it to find NCD and answer dominance queries"
This reverts commit r306892.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@306907 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This patch adds another verification function for checking correctness of findNearestCommonDominator.
For every edge from U to V in the input graph, `NCD(U, V) == IDom(V) or V` -- the new function checks this condition.
Reviewers: dberlin, sanjoy, chandlerc
Reviewed By: dberlin
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D34575
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@306893 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This patch makes DomTreeNodes keep their level (depth) in the DomTree. By having this information always available, it is possible to speedup and simplify findNearestCommonDominator and certain dominance queries.
In the future, level information will be also needed to perform incremental updates.
My testing doesn't show any noticeable performance differences after applying this patch. There may be some improvements when other passes are thought to use the level information.
Reviewers: dberlin, sanjoy, chandlerc, grosser
Reviewed By: dberlin
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D34548
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@306892 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
DFS InOut numbers currently get eagerly computer upon DomTree construction. They are only needed to answer dome dominance queries and they get invalidated by updates and recalculations. Because of that, it is faster in practice to compute them lazily when they are actually needed.
Clang built without this patch takes 6m 45s to boostrap on my machine, and with the patch applied 6m 38s.
Reviewers: sanjoy, dberlin, chandlerc
Reviewed By: dberlin
Subscribers: davide, llvm-commits
Differential Revision: https://reviews.llvm.org/D34296
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@306778 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This patch adds an additional level of verification - it checks parent and sibling properties of a tree. By definition, every tree with these two properties is a dominator tree.
It is possible to run those check by running llvm with `-verify-dom-info=1`.
Bootstrapping clang and building the llvm test suite with this option enabled doesn't yield any errors.
Reviewers: dberlin, sanjoy, chandlerc
Reviewed By: dberlin
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D34482
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@306711 91177308-0d34-0410-b5e6-96231b3b80d8
Summary: Helper functions (DFSPass, ReverseDFSPass, Eval) need SemiNCAInfo anyway, so it's simpler to have them there as member functions. This also makes them simpler by removing template boilerplate.
Reviewers: dberlin, sanjoy, chandlerc
Reviewed By: dberlin
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D34427
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@306579 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This moves SemiNCAInfo from DeminatorTreeBase to GenericDomTreeConstruction. It also put helper functions used during tree constructions in the same file.
The point of this change is to further clean up DominatorTreeBase and make it easier to construct and verify (in future patches).
Reviewers: dberlin, sanjoy, chandlerc
Reviewed By: dberlin
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D34420
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@306576 91177308-0d34-0410-b5e6-96231b3b80d8
Summary: The temporary IDoms map was used only during DomTree calculation. We can move it to SNCAInfo so that it's no longer a DominatorTreeBase member.
Reviewers: sanjoy, dberlin, chandlerc
Reviewed By: dberlin
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D34317
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@306574 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
The InfoRec struct is used only during tree construction, so there is no point having it as a DominatorTreeBase member.
This patch moves it into the Calculate function instead and makes it pass it to its helper functions.
Reviewers: sanjoy, dberlin, chandlerc
Reviewed By: dberlin
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D34305
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@306572 91177308-0d34-0410-b5e6-96231b3b80d8
Summary: Number to node mapping in DominatorTreeBase is used only during calculation, so there is no point keeping is as a member variable. This patch moves this mapping to Calculate function and passes it to helper functions. It also makes the name more descriptive.
Reviewers: sanjoy, dberlin, davide, chandlerc
Reviewed By: dberlin
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D34295
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@306562 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This patch makes GenericDomTreeConstruction use the Semi-NCA algorithm instead of Simple Lengauer-Tarjan.
As described in `RFC: Dynamic dominators`, Semi-NCA offers slightly better performance than SLT. What's more important, it can be extended to perform incremental updates on already constructed dominator trees.
The patch passes check-all, llvm test suite and is able to boostrap clang. I also wasn't able to observe any compilation time regressions.
Reviewers: sanjoy, dberlin, chandlerc, grosser
Reviewed By: dberlin
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D34258
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@306437 91177308-0d34-0410-b5e6-96231b3b80d8
Summary: This patch cleans up GenericDomTreeConstruction by replacing typedefs with usings and replaces `typename GraphT::NodeRef` with `NodePtr` to make the file more readable.
Reviewers: sanjoy, dberlin, chandlerc
Reviewed By: dberlin
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D34254
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@305715 91177308-0d34-0410-b5e6-96231b3b80d8
and also "clang-format GenericDomTreeConstruction.h, since the current
formatting makes it look like their is a bug in the loop indentation, and there
is not"
This reverts commit r296535.
There are still some open design questions which I would like to discuss. I
revert this for Daniel (who gave the OK), as he is on vacation.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@296812 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Currently, our post-dom tree tries to ignore and remove the effects of
infinite loops. It fails miserably at this, because it tries to do it
ahead of time, and thus can only detect self-loops, and any other type
of infinite loop, it pretends doesn't exist at all.
This can, in a bunch of cases, lead to wrong answers and a completely
empty post-dom tree.
Wrong answer:
```
declare void foo()
define internal void @f() {
entry:
br i1 undef, label %bb35, label %bb3.i
bb3.i:
call void @foo()
br label %bb3.i
bb35.loopexit3:
br label %bb35
bb35:
ret void
}
```
We get:
```
Inorder PostDominator Tree:
[1] <<exit node>> {0,7}
[2] %bb35 {1,6}
[3] %bb35.loopexit3 {2,3}
[3] %entry {4,5}
```
This is a trivial modification of the testcase for PR 6047
Note that we pretend bb3.i doesn't exist.
We also pretend that bb35 post-dominates entry.
While it's true that it does not exit in a theoretical sense, it's not
really helpful to try to ignore the effect and pretend that bb35
post-dominates entry. Worse, we pretend the infinite loop does
nothing (it's usually considered a side-effect), and doesn't even
exist, even when it calls a function. Sadly, this makes it impossible
to use when you are trying to move code safely. All compilers also
create virtual or real single exit nodes (including us), and connect
infinite loops there (which this patch does). In fact, others have
worked around our behavior here, to the point of building their own
post-dom trees:
https://zneak.github.io/fcd/2016/02/17/structuring.html and pointing
out the region infrastructure is near-useless for them with postdom in
this state :(
Completely empty post-dom tree:
```
define void @spam() #0 {
bb:
br label %bb1
bb1: ; preds = %bb1, %bb
br label %bb1
bb2: ; No predecessors!
ret void
}
```
Printing analysis 'Post-Dominator Tree Construction' for function 'foo':
=============================--------------------------------
Inorder PostDominator Tree:
[1] <<exit node>> {0,1}
:(
(note that even if you ignore the effects of infinite loops, bb2
should be present as an exit node that post-dominates nothing).
This patch changes post-dom to properly handle infinite loops and does
root finding during calculation to prevent empty tress in such cases.
We match gcc's (and the canonical theoretical) behavior for infinite
loops (find the backedge, connect it to the exit block).
Testcases coming as soon as i finish running this on a ton of random graphs :)
Reviewers: chandlerc, davide
Subscribers: bryant, llvm-commits
Differential Revision: https://reviews.llvm.org/D29705
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@296535 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Convert all obvious node_begin/node_end and child_begin/child_end
pairs to range based for.
Sending for review in case someone has a good idea how to make
graph_children able to be inferred. It looks like it would require
changing GraphTraits to be two argument or something. I presume
inference does not happen because it would have to check every
GraphTraits in the world to see if the noderef types matched.
Note: This change was 3-staged with clang as well, which uses
Dominators/etc from LLVM.
Reviewers: chandlerc, tstellarAMD, dblaikie, rsmith
Subscribers: arsenm, llvm-commits, nhaehnle
Differential Revision: https://reviews.llvm.org/D29767
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294620 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
GenericDomTreeConstruction had its own written DFS walk.
It is basically identical to the DFS walk df_* is doing in the iterators.
the one difference is that df_iterator uses an internal visited set.
The GenericDomTreeConstruction one reused a field in an existing densemap lookup.
Time-wise, this way is actually more cache-friendly (the previous way has a random store
into a successor's info, the new way does that store at the same time and in the same place
as other stores to the same info)
It costs some very small amount of memory to do this, and one we pay in some other part of
dom tree construction *anyway*, so we aren't really increasing dom tree constructions's
peak memory usage.
It could still be changed to use the old field with a little work on df_ext_* if we care
(and if someone find performance regressions)
Reviewers: chandlerc
Reviewed By: chandlerc
Subscribers: Eugene.Zelenko, llvm-commits
Differential Revision: https://reviews.llvm.org/D8932
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294339 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Looking at the implementation, GenericDomTree has more specific
requirements on NodeRef, e.g. NodeRefObject->getParent() should compile,
and NodeRef should be a pointer. We can remove the pointer requirement,
but it seems to have little gain, given the limited use cases.
Also changed GraphTraits<Inverse<Inverse<T>> to be more accurate.
Reviewers: dblaikie, chandlerc
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D23593
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@278961 91177308-0d34-0410-b5e6-96231b3b80d8
The patch is generated using this command:
tools/clang/tools/extra/clang-tidy/tool/run-clang-tidy.py -fix \
-checks=-*,llvm-namespace-comment -header-filter='llvm/.*|clang/.*' \
llvm/lib/
Thanks to Eugene Kosov for the original patch!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@240137 91177308-0d34-0410-b5e6-96231b3b80d8
I haven't looked closely at exactly why the side effect is required, but
this seems better than not mentioning it at all.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226030 91177308-0d34-0410-b5e6-96231b3b80d8
